Duplicate along a path WITHOUT transform
The method you follow is fine, but you've got problems with the scale and orientation of your objects.

Lets start with the Curve.


Make sure its Origin (A, the orange dot) is located at one extremity of the curve. Otherwise, make them fit in Edit mode.
Make sure its Scale (B) is (1 1 1) and Rotation is (0 0 0): otherwise, in object mode, press Ctrl+A / Rotation and scale.




Now we'll set up the plane and its modifiers.


Make sure the plane's origin is at the same location than the curve origin : in Object mode select the Curve, Shift+S / Crursor to selected. Then add the plane.
Make sure the plane is oriented like the yellow ones in my picture. Make sure its Scale is (1 1 1) and Rotation (0 0 0), or Ctrl+A/Rotation and scale.
Add an array modifier. In Fit Type, select Fit Curve, then select your curve. Crank up the offset to space them a bit.
Add a Curve modifier, select your curve.


You should obtain something very similar than the grey planes in my picture. If not, check every step again...



Let's add the box:


Select the plane, Shift+S / Cursor to selection, Shift+A Cube.
You'll want to resize it : please, do that in Edit mode ! I'm pretty sure 90% of your problem is that you resize/rotate in object mode.
It should be oriented like in my picture.
Once again, Ctrl+A/Rotation and Scale




Make the box a child of the plane, activate Dupliface on the plane. Tada! Once you're here, you'll probably want to disable Render Instancer (so only the boxes will be rendered, not the planes).